7 articles
Cisco

Leeched from http://www.cyberflunk.com/~nikm/cisco/masks.html (without permission) Cisco Netmasks, CIDR sizes, and Inverse Masks The address/netmask syntax of 172.16.35.0/255.255.255.0 should be familiar to anyone with some experience with IP routing, and is fairly easy to figure out address ranges given a calculator and a piece of scrap paper. There are other forms of addressing which are used…

Traffic which should be blocked by routers (Cisco specific) There are a number of Internet addresses and packet types which a site router should always block. In most cases there is no legitimate reason for this traffic to appear on a public network, so any occurence indicates either a misconfigured host somewhere on the Internet…

*** NOTE: this was written several years ago – but may still be useful *** VLANS Increase security and ease administration and relocation. Break up broadcast domains. VLANS work at layer 2 and 3 of OSI model. Communication between VLANs uses layer 3 routing. 3 ways of assigning a switched port to VLANs: Port-Centric –…

** note – this is several years old now – but much of it is still useful ** Cisco CCNA Certification Study Guide Ctrl+Shift+6 then X – Allows you to open more than one telnet session. Only the Hardware addresses change when packets go through routers. Half duplex Ethernet – One station can only send…

CISCO – Blocking broadcast traffic. We’ve had some requests for examples of how to filter broadcast traffic. As with a lot of things in the computer world, “there is more than one way to do it.” If your network is composed *only* of /24 allocations (ie you’re not supernetting or subnetting anywhere on class C’s,…